Search

Living shorelines (LS) stabilize eroding banks while providing more natural habitats and creating a gentler slope for enhanced migration of flora and fauna migration as sea levels rise. Typical LS practices include using several different materials, including oyster shell bags, to stabilize shorelines and planting marsh grasses. However, incorporating other important species interactions among marsh organisms can improve LS function and stability. For example, ribbed mussels, Guekensia demissa, benefit marsh plants by adding nutrients and stabilizing sediments. Unfortunately, mussels are not typically included in management and restoration practices. In this study, the objective was to investigate whether ribbed mussels facilitate marsh grass growth at a LS site in the southeastern US. We conducted field surveys for mussel abundance and recruitment, and a manipulative in situ experiment at an established LS site in Georgia to explore the impacts of adding mussels. Although mussel treatment did not have a significant effect on Spartina alterniflora metrics (i.e., density, height, biomass), Spartina plots with high mussel density exhibited ~300% increase in biomass relative to the start of the experiment, while plots without mussels only increased by ~100%. Some of the variability within treatments can be explained by high and sustained mussel mortality throughout the experimental period, likely due to predation, that impacted the actual mussel densities in our plots. We found that Spartina height, density, and biomass exhibited significant positive relationships with mussel biomass. Thus, ribbed mussels may be useful in living shorelines restoration projects if they are planted in sufficient densities, in aggregations, and/or with protective devices. [ABSTRACT FROM AUTHOR]

Sea-level rise (SLR) will produce unprecedented changes in tidal marsh systems that already cope with daily tidal fluctuation, disturbances from storms, and salinity changes from droughts and runoff events. Additionally, negative impacts from non-native invasive species may alter marsh plants' ability to respond to SLR stressors like increased inundation and salinity. Increasingly, tidal marsh communities must tolerate both changes in the physical environment from SLR and increased risk of invasion by non-native species. To assess the response of a threatened tidal marsh cordgrass (Spartina foliosa) to both stressors, we implemented a field experiment in San Francisco Bay, CA, USA, exposing cordgrass to a treatment that extended tidal inundation projected with SLR using a recently developed in situ method. At one of two field sites, we also enclosed the cordgrass with or without the invasive European green crab, Carcinus maenas. We found that cordgrass responded negatively to longer inundation, although these effects varied by site and year. In higher inundation treatments, cordgrass survival increased with increasing surface elevation of the plot. Cordgrass survival was lower in the presence of invasive green crabs relative to controls. We did not find interacting effects of responses to increased inundation and invasive species presence, which highlights the need to consider how latent or sequential effects of multiple stressors may affect ecosystems. This study demonstrates significant biological responses to invasive species presence and increased inundation. Evaluating relative effects and timing of multiple stressors, especially those induced by climate change and invasive species, will help us to manage threatened ecological communities in a changing world. [ABSTRACT FROM AUTHOR]

Coastal marsh ecosystems are changing and being lost at a rapid rate around the world. One of the fastest rates of land loss, specifically coastal marsh habitat, occurs in Louisiana on the Northern Gulf Coast of the USA. To address this issue, state and federal agencies have undertaken massive wetland restoration efforts to preserve and restore coastal marsh habitats in Louisiana. For these efforts to be successful in the long-term, it is critical to understand what methodologies and techniques result in resilient restoration projects. However, traditional methods to monitor restoration success rely on labor intensive field measurements that are often limited in scope, difficult to maintain, and underfunded. Recent technological developments with uncrewed aircraft systems (UASs) and image processing have substantially improved the ability of restoration practitioners to use off-the-shelf UASs and cameras to map projects. We present a streamlined method using a commercially available drone with a high-resolution red, green, blue (RGB) camera to assess the effects of wetland restoration and integrate more modern tools into evaluation approaches. We conducted drone flights at restored brackish marshes of various ages using a space for time substitution with the goal of understanding the long-term success of marsh restoration. We observed that created marshes had higher land to water ratios than natural marshes. This finding suggests that these restored areas were gaining and maintaining elevation after approximately 10 years. Our method shows that drone surveys offer low-cost, minimally invasive methods for evaluating restored wetlands and ultimately tell us more about ecosystem function through realistic site-level habitat configurations. [ABSTRACT FROM AUTHOR]

Climate‐driven ecosystem shifts occur through turnover in the foundation species which structure the landscape. Therefore, to predict the fate of areas undergoing climate‐driven ecosystem shifts, one approach is to characterize ecological and evolutionary responses of foundation species along dynamic environmental gradients. One such gradient is the ecotone between tidal marshes and maritime forests in coastal areas of the US Mid‐Atlantic region where accelerated sea‐level rise and coastal storms of increased frequency and intensity are driving forest dieback and inland marsh migration. Mid‐Atlantic tidal marshes are structured by marsh grasses which act as foundation species, and these grasses exhibit trait variation across their distribution from established marsh interior to their inland migration front. We conducted a reciprocal transplant experiment with Spartina patens, a dominant high marsh grass and foundation species, between established populations in the high marsh and range edge populations in the forest understory at three Mid‐Atlantic sites. We monitored environmental conditions in marsh and forest understory habitats, measured plant traits (above‐ and belowground biomass, specific leaf area, leaf N and C concentrations) in transplanted and reference non‐transplanted individuals, and used microsatellite markers to determine the genetic identity of transplants to quantify clonality between habitats and sites. Individuals transplanted into the forest understory exhibited a plastic shift in resource allocation to aboveground structures associated with light acquisition, with shifts in transplants making them more morphologically similar to reference individuals sampled from the forest habitat. Clonal diversity and genetic distance among transplants were relatively high at two of three sites, but individuals at all sites exhibited trans‐habitat plasticity regardless of clonal diversity or a lack thereof. Individuals grown in the forest understory showed lower vegetative and reproductive fitness. Nevertheless, the trait plasticity exhibited by this species allowed individuals from the forest that were transplanted into the marsh to recoup significant biomass in only a single growing season. We predict high plasticity will facilitate the persistence of colonizing S. patens individuals under suboptimal forest shade conditions until forest dieback increases light availability, ultimately promoting continued inland migration of this foundation species under sea‐level rise. [ABSTRACT FROM AUTHOR]

Coastal vegetated ecosystems including mangroves, seagrasses, and salt marshes are often shaped by positive plant–environment feedbacks. Plants improve their own living conditions with increasing patch size and density by attenuating hydrodynamics and stabilizing sediments. As these habitat modifications are critical for survival and growth, the positive density‐dependent nature of these feedbacks can lead to establishment thresholds for young plants in absence of mature conspecifics. Although feedback strength is known to depend on hydrodynamic exposure and plant traits (e.g. stiff versus flexible stems), it remains unclear how 1) opposing morphological plant traits affect establishment in contrasting environments, and 2) whether trait plasticity influences establishment success. Here, we investigate this by transplanting two tidal species with opposing growing strategies – Spartina anglica forms tussocks of stiff stems while Zostera noltii forms patches of stress‐avoiding flexible shoots – from two different donor sites in eight experimental locations. Results show that the survival and growth of both species was most successful at field locations with diverging environmental characteristics, while overall survival was highest for Z. noltii. Mainly, S. anglica survival was highest at locations with high organic matter and silt content and higher elevation relative to the tidal amplitude. In contrast, Z. noltii survival was highest at locations with larger grainsize and lower relative elevations. Furthermore, despite initial differences in plant traits between the two donor sites of Z. noltii, we found no effects of donor origin. Contrastingly, we found a significant effect of donor origin on S. anglica growth, even though transplants from the two donor sites showed no initial trait differences. Collectively, these results suggest that the stress‐tolerance strategy of S. anglica hampers establishment in exposed conditions, whereas the stress‐avoiding Z. noltii appears to be more susceptible to stress from desiccation and silty sediments. [ABSTRACT FROM AUTHOR]

Spartina anglica, an invasive marsh grass, was designated as a harmful marine organism in 2016 due to its ability to stabilize mudflats and reduce macrobenthic diversity. To control such invasive species, physical, chemical, or biological methods can be applied while chemical methods are prohibited by law due to ecological disruption. However, the preferred methods of soil tillage, cutting, and native plant restoration for managing S. anglica have rarely been analyzed. To compare the methods, we performed 9 treatments with four replicates, comprising control, different frequencies of clipping (once and twice) and tilling (once and twice), and different densities (50 and 100 seedling) of restoration of the native plants Suaeda japonica and Phragmites australis. To evaluate the severity of disturbance, we measured coverage, stem density, average plant height, and above-ground biomass for 2 years. We found P. australis and S. japonica did not successfully establish or survive due to niche differences and the inherent biological features of Spartina. However, physical removal had a stronger effect than interspecific interaction. Two cutting treatments in the early and the late growing season reduced plant height and biomass of S. anglica by 6 and 34%, respectively, compared with the control treatment at the rapid vegetative growth stage in the following year. We also found that two tillage treatments reduced biomass, plant cover, and stem density by 32%, 38%, and 83%, respectively, in the following year. In the study site, managing invasive species such as S. anglica is best achieved by physically destroying the plant using soil tillage while attempting to restore native species had marginal control effects. [ABSTRACT FROM AUTHOR]

Intercropping kura clover (Trifolium ambiguum) (KC) with prairie cordgrass (Spartina pectinata) (PCG) has great potential for biofuel feedstock on marginal lands. This study evaluated the impacts of 10‐year PCG‐KC intercropping and PCG monoculture fertilized with different nitrogen (N) rates of granular urea (five treatments: PCG‐KC, PCG‐0N, PCG‐75N, PCG‐150N, and PCG‐225N) on soil biogeochemical properties: (i) in the surface soil (0‐ to 10‐cm depth) at three different sampling times during the crop growing season: spring (April, pre‐emergence), summer (June, active growth), and fall (November, post‐harvest); and (ii) at different soil depths (0–5, 5–15, 15–30, 30–45, and 45–60 cm) (only total carbon (C) and N) in fall 2021. All soil biogeochemical parameters were higher during summer as compared to spring and/or fall, except urease activity, ammonium‐N, microbial biomass C and N, and fluorescein diacetate (FDA). On average over the sampling times, PCG‐KC had significantly higher β‐glucosidase activity and hot‐water extractable organic N than PCG‐0N; but no significant difference between PCG‐KC and N‐fertilized PCG. Cold‐water extractable organic N was significantly lower than the highest N rate, but not significantly different from PCG‐0N and lower N rate treatments. Urease activity under PCG‐KC treatment was double that of PCG‐0N and PCG‐75N; FDA was higher in PCG‐KC than all monocultures. No treatment effect was found on soil total C and N, except that they decreased with depth. Overall, intercropping PCG‐KC showed some benefits in terms of promoting soil biogeochemical properties during crop growth periods, having lower residual reactive N in the soil, and maintaining biomass yield and quality on marginal lands. Core Ideas: On average over the crop growing season, intercropping prairie cordgrass and kura clover had higher soil β‐glucosidase, urease, and fluorescein diacetate enzyme activity as compared to zero N treatment.Overall, urease activity with intercropping prairie cordgrass and kura clover was higher as compared to low N fertilizer treatment, while fluorescein diacetate enzyme activity was higher as compared to all N fertilizer rate treatments.Intercropping prairie cordgrass and kura clover had lower residual soil nitrate‐N concentrations than high N rate treatments.Soil total carbon and nitrogen measured in fall (November) were similar among intercropping and urea fertilizer rate treatments at 0‐ to 60‐cm depth.Intercropping prairie cordgrass and kura clover did not affect aboveground biomass yield and forage quality. [ABSTRACT FROM AUTHOR]

Abstract Climate‐driven ecosystem shifts occur through turnover in the foundation species which structure the landscape. Therefore, to predict the fate of areas undergoing climate‐driven ecosystem shifts, one approach is to characterize ecological and evolutionary responses of foundation species along dynamic environmental gradients. One such gradient is the ecotone between tidal marshes and maritime forests in coastal areas of the US Mid‐Atlantic region where accelerated sea‐level rise and coastal storms of increased frequency and intensity are driving forest dieback and inland marsh migration. Mid‐Atlantic tidal marshes are structured by marsh grasses which act as foundation species, and these grasses exhibit trait variation across their distribution from established marsh interior to their inland migration front. We conducted a reciprocal transplant experiment with Spartina patens, a dominant high marsh grass and foundation species, between established populations in the high marsh and range edge populations in the forest understory at three Mid‐Atlantic sites. We monitored environmental conditions in marsh and forest understory habitats, measured plant traits (above‐ and belowground biomass, specific leaf area, leaf N and C concentrations) in transplanted and reference non‐transplanted individuals, and used microsatellite markers to determine the genetic identity of transplants to quantify clonality between habitats and sites. Individuals transplanted into the forest understory exhibited a plastic shift in resource allocation to aboveground structures associated with light acquisition, with shifts in transplants making them more morphologically similar to reference individuals sampled from the forest habitat. Clonal diversity and genetic distance among transplants were relatively high at two of three sites, but individuals at all sites exhibited trans‐habitat plasticity regardless of clonal diversity or a lack thereof. Individuals grown in the forest understory showed lower vegetative and reproductive fitness. Nevertheless, the trait plasticity exhibited by this species allowed individuals from the forest that were transplanted into the marsh to recoup significant biomass in only a single growing season. We predict high plasticity will facilitate the persistence of colonizing S. patens individuals under suboptimal forest shade conditions until forest dieback increases light availability, ultimately promoting continued inland migration of this foundation species under sea‐level rise.

Invasive species are known to alter the progress of ecological restoration, but effects of invasive consumers, and particularly those that can act through both trophic and physical disturbance mechanisms, remain poorly understood. Due to its impacts on vegetation and ability to alter marsh food webs, we predicted that a non-native crab, Carcinus maenas (European green crab), would negatively affect restoration plantings of a native cordgrass, Spartina foliosa 1 (California cordgrass), in San Francisco (SF) Bay, in contrast with neutral or positive impacts predicted for a native crab, Hemigrapsus oregonensis (yellow shore crab). We implemented an experiment in SF Bay using caged plots of planted S. foliosa , to which we added or did not add crabs. We compared responses among these treatments, cageless, and partially-caged controls. Carcinus maenas treatments had the greatest reduction in S. foliosa stem density from June through August, and the lowest stem density in August relative to all other treatments. Hemigrapsus oregonensis effects were similar to controls. Both crabs reduced small invertebrate abundance by ~50% and led to shifts in community composition relative to controls. Changes to the invertebrate community and subtle shifts in soil conditions may contribute to the apparent negative impact of C. maenas. Crab trapping revealed more C. maenas in areas with Spartina in SF Bay, suggesting it uses Spartina as a refuge and that these effects are especially relevant to restoration activities. These results add to our developing understanding that invasive consumers can affect the path and pace of restoration and thus warrant increased attention in restoration planning and management. [ABSTRACT FROM AUTHOR]

Plant invasions driven by global environmental changes (e.g. nutrient enrichment) increasingly threaten natural ecosystems. It is unclear whether reducing nitrogen (N) inputs helps to mitigate plant invasions in natural ecosystems.Using ongoing, landscape‐scale N reductions in the Yangtze River, we combined spatiotemporal surveys before and after reducing N inputs and manipulative experiments to explore how N reductions contributed to native community recovery in estuarine marshes degraded by plant invasions.We found that native Phragmites australis patches gradually recovered in Spartina alterniflora‐invaded marshes after reducing N inputs. The competitive advantage of S. alterniflora over P. australis decreased with N reduction, shifting the competitive outcomes away from P. australis exclusion to their coexistence.Synthesis and applications. Our findings reveal that the reversal of nitrogen enrichment may shift ecosystems from being more susceptible to invasion toward successional recovery, offering a promising approach for facilitating native community recovery in the invaded ecosystems. These findings have important implications for restoring invaded ecosystems, especially as global environmental change escalates the extent and impact of invaders by exacerbating current invasions and facilitating new ones. [ABSTRACT FROM AUTHOR]

Spartina alterniflora Loisel, widely recognized as an aggressive invader of estuaries and salt marshes worldwide, was recently reported in Korean waters as rapidly invading intertidal mudflats, growing in circular patches. For more effective control management of the invasive cordgrass, we developed a modified ignition logistic model based on the satellite imageries to estimate the settlement time of the first individual stand and the doubling period of the patch spread in the early colonization state. The present model is designed for estimating the starting time and the doubling period of the patch spread at the growth stage, which is a salient feature different from other logistic models. The importance of estimating the starting time of the invasion may lie in figuring out what ecological changes occurred at that time. A Monte-Carlo simulation is combined with our model to obtain reliable predictions against the noisy data. As a result of applying the model to the Northwest Pacific invading tidal flats of Korea, China, and Japan, it turns out that the doubling periods of the patch spread are generally shorter and similar to each other, which range from 0.6 to 2.1 years. This is probably attributed to the genetically hybridized populations of Spartina alterniflora invading this region. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate water conservation strategies in the above ground parts of Desmostachya bipinnata L., a perennial grass growing in populations of arid areas of the Punjab to identify variability in the anatomical traits that enable them to survive in water deficit conditions. Key structural modifications contributing to the ecological success and adaptation against heterogeneous environments included water conservation via development of additional water storage parenchyma, efficient conduction of solutes through wide metaxylem vessel (7947 µm2), minimization of water loss by intensive sclerification in some populations from Kallar Kahar (hyper-saline lake) and Pakka Anna (highly saline wasteland with Dratio:13.29) to avoid water loss. Populations from the most dry habitats, that is, in Cholistan (inter-dune desert flat with Dratio:43.17) had numerous small metaxylem vessels (1727 µm2). Saluwali (Cholistan Desert plain Dratio:30.4) populations showed intensive sclerification in stem vascular region and high density, wider metaxylem vessel oriented in dimensions different than other populations. A very unique feature observed in stems of Cholistan desert margin Kachakho, Pirowal plantation and Saluwali populations was the development of single-large metaxylem vessels instead of a pair usually found in plants. Another characteristic feature observed in stems, leaves and leaf sheath of some populations was differentially developed aerenchyma and bulliform cells ranging from small to large prominent and deeply inserted. In conclusion, D. bipinnata populations showed high but habitat-specific variability among the traits recorded, which provided this species a great potential to colonize arid and salt-affected areas. [ABSTRACT FROM AUTHOR]

Copyright of Ecological Applications is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The high elevation salt marsh plant Spartina patens can potentially cope with accelerated sea level rise by migrating inland, but the ability to do so may differ among plant ecotypes. We compared performance among ecotypes collected from three different sites within mesocosms in which we manipulated soil type, plant litter and salinity. Half of our treatment levels simulated conditions plants would encounter when expanding into terrestrial environments (i.e., upland soil, litter present and low salinity); the other half expansion into tidal creeks (i.e., marsh soil, litter absent, and high salinity). Plant litter and salinity did not significantly affect aboveground biomass or rhizome growth and only affected flowering in a three-way interaction with site. However, all three parameters were significantly affected by soil conditions and the site × soil interaction. Upland soil conditions reduced aboveground biomass, rhizome growth and flowering, as compared to marsh soil conditions, for ecotypes from some sites but not others. When just comparing plant performance in the upland soil treatment, ecotypes from some collection sites did better than others. One plausible explanation for this ecotypic variation is pre-adaptation to differences we found in organic matter content among our collection sites, with the ecotype collected from the site with the lowest organic matter content generally being least impacted by upland soil conditions. Our results indicate that S. patens ecotypes can vary in their capacity to successfully expand into uplands, and thus we suggest prioritizing conservation of such ecotypes, as well as their use in restoration efforts. Consideration of ecotypic variation might also prove useful in deciding where to focus conservation efforts for marsh migration. [ABSTRACT FROM AUTHOR]

Tidal marsh insect communities are influenced by both salinity and aspects of vegetation texture (vegetation diversity, plant density, and architectural structure). These factors affect the abundances and intra‐ and interguild interactions of these insects and should result in broad‐scale variation in the distribution and ecological functioning of tidal marsh insect communities along these gradients. However, this assumption has not been tested within Gulf Coast marshes, and the insect communities and their ecological roles are not well known. This study identifies how family‐level insect biodiversity varies by salinity and which factors are most important in affecting the distribution of insect functional feeding groups within Louisiana's coastal marshes. Insect family diversity was found to decrease as salinity increased for several indices. Vegetation texture and the underlying salinity gradient were found to be important factors affecting the distribution of free‐living sucking, stem‐boring, parasitic, and filtering functional feeding groups. [ABSTRACT FROM AUTHOR]

Tidal wetlands are important blue carbon reservoirs, but it is unclear how sea-level rise (SLR) may affect carbon cycling and soil microbial communities either by increased inundation frequency or via shifting plant species dominance. We used an in-situ marsh organ experiment to test how SLR-scenarios (0, + 7.5, + 15 cm) and vegetation treatments (Spartina alterniflora, Spartina patens, Phragmites australis, unvegetated controls) altered CO2 fluxes (net ecosystem exchange, ecosystem respiration), soil carbon mineralization rates, potential denitrification rates, and microbial community composition. Increasing inundation frequency with SLR treatments decreased the carbon sink strength and promoted carbon emissions with + 15-cm SLR. However, SLR treatments did not alter soil chemistry, microbial process rates, or bacterial community structure. In contrast, our vegetation treatments affected all carbon flux measurements; S. alterniflora and S. patens had greater CO2 uptake and ecosystem respiration compared to P. australis. Soils associated with Spartina spp. had higher carbon mineralization rates than P. australis or unvegetated controls. Soil bacterial assemblages differed among vegetation treatments but shifted more dramatically over the three-month experiment. As marshes flood more frequently with projected SLR, marsh vegetation composition is predicted to shift towards more flood-tolerant S. alterniflora, which may lead to increased CO2 uptake, though tidal marsh carbon sink strength will likely be offset by increased abundance of unvegetated tidal flats and open water. Our findings suggest that plant species play a central role in ecosystem carbon dynamics in vegetated tidal marshes undergoing rapid SLR. [ABSTRACT FROM AUTHOR]

Abstract Tidal marsh insect communities are influenced by both salinity and aspects of vegetation texture (vegetation diversity, plant density, and architectural structure). These factors affect the abundances and intra‐ and interguild interactions of these insects and should result in broad‐scale variation in the distribution and ecological functioning of tidal marsh insect communities along these gradients. However, this assumption has not been tested within Gulf Coast marshes, and the insect communities and their ecological roles are not well known. This study identifies how family‐level insect biodiversity varies by salinity and which factors are most important in affecting the distribution of insect functional feeding groups within Louisiana's coastal marshes. Insect family diversity was found to decrease as salinity increased for several indices. Vegetation texture and the underlying salinity gradient were found to be important factors affecting the distribution of free‐living sucking, stem‐boring, parasitic, and filtering functional feeding groups.

Demand for energy and the environmental consequences associated with fossil fuel emissions has created a need for alternative energy sources. To avoid conflict over the conversion of existing agricultural land from food production to fuel production, bioenergy crops could instead be cultivated on marginal land. This study compared the performances, biomass yield, tiller density, and lignocellulosic bioenergy feedstock composition of four prairie cordgrass populations with two-row spacings cultivated on a waterlog-prone marginal land, as well as three other bioenergy candidate crops used as controls: big bluestem, M. × giganteus, and switchgrass. Across all populations and spacings, annual biomass yield of prairie cordgrass was 13 Mg ha−1. Row spacing had significant impacts on prairie cordgrass productivity, with higher biomass yields observed in the 45 cm spacing than in the 90 cm spacing. Feedstock composition (cellulose, hemicellulose, ADL, and ash concentration) was not influenced by row spacing and did not deviate from expected values for growth on agricultural lands. However, biomass yields of the control species M. × giganteus and switchgrass planted in 45 cm spacing were higher than the prairie cordgrass. Our results provide evidence that prairie cordgrass could be a good energy crop with comparable biomass yield production to the energy crops M. × giganteus and switchgrass on waterlogged marginal land. [ABSTRACT FROM AUTHOR]

Vegetation changes in saltmarsh habitat can influence fish assemblages and abundance. In Tasmania, Australia, mid‐latitude succulent saltmarsh communities have been invaded by the introduced tall grass, Spartina anglica. Eradication efforts have been ongoing since the 1990s with purported benefits for fish access to intertidal foraging grounds, but a lack of knowledge of the impact of S. anglica on fish limits understanding of the benefits and effectiveness of native habitat restoration. Here, we investigate whether fish assemblages in native saltmarshes and non‐native S. anglica grassland differ in species diversity, fish abundance, and size class distribution. We used buoyant pop nets to sample fishes in Sarcocornia quinqueflora herbland and S. anglica grassland swards at three sampling stations in northwest Tasmania. Very few individuals and low species diversity were recorded in both vegetation types at the sampling station with the most well‐established S. anglica infestation. Elsewhere, richness and diversity were higher in S. quinqueflora herbland. Overall fish abundance was higher in S. quinqueflora than in S. anglica, with a very strong effect at one sampling station. Fewer small individuals of the numerically dominant Atherinosoma microstoma were recorded in S. anglica, potentially indicating impaired nursery function. Our results provide important insights for S. anglica control, as we are the first to demonstrate a relationship between S. anglica presence and fish characteristics in southern Australian saltmarsh. These results indicate that S. anglica control is valuable for fish conservation. An extension of our research to document the effects of S. anglica removal on fishes is desirable. [ABSTRACT FROM AUTHOR]

Many ixodid species on the South Texas coastal plain can transmit pathogens to their hosts. Substantial areas are dominated by gulf cordgrass, Spartina spartinae (Trin.) Merr. ex Hitch. The S. spartinae habitat was examined in terms of abiotic and biotic factors that likely impinge upon ixodids using the plant for questing. Natural enemies, temperature, humidity, and plant structure were investigated as possible mortality factors and improving ixodid survival. Spartina spartinae (soil and foliage) harbored few natural enemies of ixodids, and soil salinity was nonlethal. Conditions were cooler and more humid inside S. spartinae clumps than in the canopies; hence, questing ixodids can rehydrate inside the clump when threatened by desiccation. Leaves were mostly "V" shaped in cooler months and, during warm months, the tightly folded leaf slot predominated, into which larvae crawled. Immature ixodids were more abundant in the concave side of the "V"-shaped leaves than on the exposed convex side. Larvae sought refuge from potential lethal ambient air conditions by entering tight warm season leaf folds. The leaf "V" and fold offer opportunities for rehydration on the leaf without moving to the clump's base. In addition to five other species collected on the grass, a relatively heavy larval southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini), population was detected, suggesting that abundances in the South Texas cattle fever tick eradication quarantine zone are increasing and might spread further into Texas. [ABSTRACT FROM AUTHOR]

Increasingly cultivated all over the world, energy crops, with their large biomass production, can be used to produce liquid biofuel and biogas. The aim of the research was to evaluate the yield and selected energy parameters of prairie cordgrass (Spartina pectinata L.) treated with different doses of municipal sewage sludge and mushroom substrate. Heat of combustion, calorific values and ash content were investigated in the first three years of its cultivation. Carried out between 2018 and 2020, the research was based on a field experiment established at an experimental facility in Central-Eastern Poland. Organic waste doses, each of them introducing 170 kg N ha−1, were applied once in spring 2018 before planting pieces of Spartina pectinata rhizomes. The experimental factors (organic waste doses and years of research) significantly affected the yield of prairie cordgrass. Significantly, the highest yield of its biomass was produced in response to municipal sewage sludge applied together with mushroom substrate (O25 + PP75) and in response to mushroom substrate applied on its own (SMS). Those values, averaged over three years of research, were, respectively, 4.23 and 4.18 Mg ha−1. Organic waste treatment had a significant impact on ash content in dry matter. On average, the highest ash content in dry matter was recorded in response to mushroom substrate (5.73%) and the lowest (4.98%) in plants treated with the highest dose of sewage sludge together with the lowest dose of mushroom substrate (O75 + PP25). The higher dry matter content in plant biomass was, the better the energy parameters were. [ABSTRACT FROM AUTHOR]

Atmospheric CO2 enrichment, which is caused to a large extent by anthropogenic activities, is known to interfere with sediment microbial communities via plant rhizospheres. The present work aimed to evaluate this interaction in Spartina maritima ((Curtis) Fernald.) rhizosediments, aiming to depict the impacts of atmospheric CO2 increase in the biogeochemical processes occurring in the rhizosphere of this pioneer and highly abundant Mediterranean halophyte. For this purpose, mesocosms trials were conducted, exposing salt marsh cores with S. maritima and its sediments to 410 and 700 ppm of CO2 while assessing rhizosediment extracellular enzymatic activities. An evident increase in dehydrogenase activity was observed and directly linked to microbial activity, indicating a priming effect in the rhizosphere community under increased CO2. Phosphatase showed a marked increase in rhizosediments exposed to elevated CO2, denoting a higher requirement of phosphate for maintaining higher biological activity rates. High sulphatase activity suggests a possible S-limitation (microbial or plant) due to elevated CO2, probably due to higher sulphur needs for protein synthesis, thus increasing the need to acquire more labile forms of sulphur. With this need to acquire and synthesize amino acids, a marked decrease in protease activity was detected. Most carbon-related enzymes suffered an increase under increased CO2. Overall, a shift in sediment extracellular enzymatic activity could be observed upon CO2 fertilization, mostly due to priming effects and not due to changes in the quality of carbon substrates, as shown by the sediment stable isotope signatures. The altered recycling activity of organic C, N, and P compounds may lead to an unbalance of these biogeochemical cycles, shifting the rhizosphere ecosystem function, with inevitable changes in the ecosystem services level. [ABSTRACT FROM AUTHOR]

Physical modeling studies have endeavored to quantify the influence of plant biophysical parameters and hydrodynamics on wave-vegetation interactions and coastal protection. The accuracy with which such studies have characterized stem motion is limited by the predominant use of plant surrogates, and the few saltmarsh species considered in live vegetation studies. To address this, prototype-scale experiments were conducted in the outdoor Large Wave Canal of the Institut National de la Recherche Scientifique, Québec, in collaboration with the University of Ottawa and the National Research Council Canada, allowing novel characterization of live vegetation deformation under wave action. Two saltmarsh species were investigated (Spartina alterniflora, Spartina patens) under various irregular wave conditions (0.03 m< Hs <0.28 m, Ts ≈ 2.5, 10 s). Stem deformation was characterized using submerged cameras and bending angle tracking, coupled with wave height and velocity measurements. Significant differences in stem flexibility were observed between species, with S. alterniflora exhibiting more rigid stems (EIalterniflora=0.051 Nm2) than S. patens (EIpatens=0.0015 Nm2; t-test; p<0.05). The two species consequexhibited different bending angles under similar hydrodynamic conditions, expected to influence their relative coastal protection capacity. These findings provide critical insight into the design of marsh construction or restoration for coastal protection. [ABSTRACT FROM AUTHOR]

Vegetated coastal ecosystems such as salt marshes, dunes and seagrass meadows occur at the land–sea interface—a dynamic environment typified by harsh growing conditions. These ecosystems are known as biogeomorphic landscapes because their functioning depends on biophysical interactions by which organisms engineer landforms to their own benefit. The strength of such biogeomorphic feedbacks depends on plant traits, such as stem flexibility and shoot density.Recent work demonstrated that dune grasses with similar morphological traits can build contrasting landscapes due to differences in their spatial shoot organization. However, in contrast to dune grasses that trap and stabilize sand particles in aeolian landscapes, flow attenuation in aquatic environments can generate scouring around plant stems and cause uprooting, leading to establishment thresholds for young plants.Yet, it remains unknown how findings from aeolian landscapes translate to aquatic systems and how young clonally expanding plants in hydrodynamically exposed conditions overcome these establishment thresholds by optimizing shoot placement.Here, we measured shoot patterns of 90 establishing cordgrass patches Spartina anglica at 18 European field sites that cover a broad range of hydrodynamic conditions. Next, we carried out a field experiment to investigate how observed spatial shoot patterns affect plant–sediment feedbacks.Surprisingly, field survey analyses reveal highly consistent clustered shoot patterns, regardless of environmental conditions. Experimental results demonstrate that this clustered pattern minimizes scouring compared to densely clumped organizations typically observed in established patches.Synthesis. In contrast to earlier findings highlighting that establishing dune grasses optimize their landscape engineering capacity via a flexible shoot placement strategy, we find that cordgrass instead follows a fixed strategy that minimizes engineering effects in its early life stages. We suggest that marsh grasses avoid physical stress and associated establishment thresholds in their early life stage, and switch to an ecosystem engineering strategy once established. These findings shed new light on how plant traits interact with their environment to shape the landscape and pave the way for improved restoration designs by mimicking the natural shoot organization of establishing vegetation. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Gulf cordgrass (Spartina spartinae [Trin.] Merr. ex Hitchc.) and seacoast bluestem (Schizachyrium scoparium [Michx.] Nash var. littorale [Nash] Gould) are dominant native warm season grasses in the Texas Coastal Prairies and Marshes ecoregion. Mature Gulf cordgrass nutritive value is considered poor for grazing animals, while seacoast bluestem nutritive value is considered fair to good in spring and early summer. We compared season of burn effects on crude protein (CP) and neutral detergent fiber (NDF) of these grasses. Our study employed four patches (200–305 ha) burned in a patch-burn grazing system (two winter, two summer 2016). Forage samples were collected before burning and every 3 d for 40 d after burning, then weekly for 50 d. Regardless of season of burning, CP was adequate for maintaining a lactating beef cow 90 d post-burning. Although peak CP in Gulf cordgrass following burning did not differ between seasons, CP increased more quickly following winter burning, when it rose abruptly for ~6.4 d and then increased more slowly to its peak at ~30 d post burn, after which it declined. After summer burning, CP of Gulf cordgrass did not increase significantly, and then declined after reaching its peak at ~29 d post burn. Gulf cordgrass NDF declined more rapidly following summer burning than winter burning but remained low for a longer period after winter burning. In seacoast bluestem, CP increased following winter burning, peaking at ~11 d after burning, but there was little change following summer burning, which did not peak until 31 d post burn. NDF of seacoast bluestem declined similarly in both seasons. This study indicates that prescribed fire during winter is more beneficial for improving the nutritive value of Gulf cordgrass and seacoast bluestem than summer burning. [ABSTRACT FROM AUTHOR]

Salt marshes provide many important ecosystem services, and interest in their restoration is growing in response to climate change. In Maritime Canada, salt marsh restoration projects have focused on restoring tidal flow without planting. Over time, these sites can show persistent deficits in vegetation diversity. We evaluated six techniques for encouraging revegetation (plugs, field transplants, seed, wrack, tilling, and no planting) with eight native species (Carex paleacea, Juncus gerardii, Limonium carolinianum, Plantago maritima, Poa palustris, Solidago sempervirens, Sporobolus alterniflorus, and Sporobolus michauxianus) at two Bay of Fundy salt marsh restoration sites. Community recovery and plant performance (growth rate, summer and winter survival, and health) were monitored over 2 years. Planting plugs produced the highest abundance of perennial halophytes over both years with high survival rates (76.4% ± 0.02 SE), whereas plants transplanted from adjacent sites had higher mortality and slightly lower cover. All planted species survived and grew. Growth rate, health, and winter survival were all more strongly related to site than planting technique, indicating that location was more important to success than technique. We found evidence that differences in elevation, inundation, soil salinity, and soil nutrients at each site may explain these differences in performance. Plugs and field transplants may both be useful for restoration in the future and mixing methods to capitalize on respective strengths may produce best results when planting. Our results also highlight the need to tailor planting plans to individual sites as plants may respond uniquely in different situations. [ABSTRACT FROM AUTHOR]

Environmental contamination by xenobiotics represents a major threat for natural ecosystems and public health. In response, xenobiotic detoxification is a fundamental trait of organisms for developmental plasticity and stress tolerance, but the underlying molecular mechanisms remain poorly understood in plants. To decipher this process, we explored the consequences of allopolyploidy on xenobiotic tolerance in the genus Spartina Schreb. Specifically, we focused on microRNAs (miRNAs) owing to their central function in the regulation of gene expression patterns, including responses to stress. Small RNA-Seq was conducted on the parents S. alterniflora and S. maritima, their F1 hybrid S. x townsendii and the allopolyploid S. anglica under phenanthrene-induced stress (phe), a model Polycyclic Aromatic Hydrocarbon (PAH) compound. Differentially expressed miRNAs in response to phe were specifically identified within species. In complement, the respective impacts of hybridization and genome doubling were detected, through changes in miRNA expression patterns between S. x townsendii, S. anglica and the parents. The results support the impact of allopolyploidy in miRNA-guided regulation of plant response to phe. In total, we identified 17 phe-responsive miRNAs in Spartina among up-regulated MIR156 and down-regulated MIR159. We also describe novel phe-responsive miRNAs as putative Spartina-specific gene expression regulators in response to stress. Functional validation using Arabidopsis (L.) Heynh. T-DNA lines inserted in homologous MIR genes was performed, and the divergence of phe-responsive miRNA regulatory networks between Arabidopsis and Spartina was discussed. Key message: Phenanthrene-responsive microRNAs were identified in the context of allopolyploid speciation in Spartina. The results support the relative impacts of hybridization and genome doubling in miRNA-guided regulation mechanisms in response to xenobiotics. [ABSTRACT FROM AUTHOR]

Prairie cordgrass - Spartina pectinata Bosc ex Link, Poaceae family, is a warm-season, C4 perennial rhizome grass native to North America. The main objective of this research was to evaluate the quality indices of green and ensiled mass substrate, solid dry biomass of the introduced taxa of Spartina pectinata, grown in monoculture in the collections of the National Botanical Garden (Institute), Chişinău. It was established that Spartina pectinata fresh mass substrate used for anaerobic digestion contained 43 g/kg CP, 66 g/kg ash, 437 g/kg Cel, 301g/kg HC, 59 g/kg ADL, 55 g/kg TSS, with C/N = 74 and biochemical methane potential 299 l/kg, but the ensiled substrate - 44 g/kg CP, 76 g/kg ash, 473 g/kg Cel, 323 g/kg HC, 57 g/kg ADL, with C/N = 72 and biochemical methane potential 303 l/kg, respectively. It has been determined that prairie cordgrass solid dry biomass harvested in winter period contained 453 g/kg Cel, 294 g/kg HC, 82 g/kg ADL, the estimated theoretical ethanol yield averaged 543 L/t. The prepared solid fuel, briquettes and pellets, had significantly higher net calorific value than perennial sorghum and corn stem fuel. The investigated introduced taxa of prairie cordgrass, may be used as multi-purpose feedstock for renewable energy production in Moldova. [ABSTRACT FROM AUTHOR]

Dense monocultures of the grass Spartina alterniflora dominate the low marsh in typical New England tidal marshes. These marshes provide a number of important ecosystem services; thus, it is important to understand the factors that influence S. alterniflora productivity. End of season live biomass is often used to estimate S. alterniflora productivity, but this measure fails to account for stems lost within the growing season and may lead to a significant underestimate. We explored two possible factors that may influence S. alterniflora stem loss within the growing season: (1) density-dependent mortality (self-thinning), and (2) the physical force of moving water via tidal action. At four tidal creeks in the Plum Island Sound estuary, Massachusetts, we found that on average 34% of the S. alterniflora stems present in June were lost by August, but this varied from 11 to 44% among creeks. This stem loss accounted for at least 20% of the estimated annual productivity. We found little evidence that tidal action drives spatial variation in stem loss. Seasonal stem loss was greater in stands with higher early season density, consistent with self-thinning. As self-thinning occurred, density became more similar among creeks, meaning that end of the season density patterns are not reflective of early season stands. Adding a simple measure of early season stem density can improve productivity estimates by incorporating loss due to self-thinning. [ABSTRACT FROM AUTHOR]

Spartina anglica (hereafter Spartina) is an invasive perennial marsh grass shifting hydrodynamic regime and sediment characteristics in invaded area, thereby reducing macrobenthic diversity. There have been only a few studies focusing on the patch structure of Spartina according to size and its effects on macrofauna. A field experiment was conducted to identify effects of Spartina patches where they have been introduced no later than 5 years after invasion occurred on macrofauna assemblages in Ganghwa Island, South Korea. The survey area was divided into two sections according to vegetation: (1) Suaeda japonica vegetation from 0 to 60 m away from the levee, and (2) bare mudflat from 60 to 90 m away from the levee. The patch sizes of Spartina were categorized into small (1–4 m2), medium (5–11 m2), and large (13–40 m2) in area with four replicates for each section. The biomass ratio of the belowground and aboveground in the small size patch of Spartina was significantly higher than those in the medium and large size patch of Spartina. It indicated that more resource was allocated to rhizomes in small size patch with short invasion history (1 ~ 2 years). After Spartina invaded, macrofauna richness (70%), Shannon–Wiener diversity (80%), and density (67%) were decreased. However, infaunal deposit-feeding polychaete Perinereis linea and epifaunal gastropods Batillaria cumingi and Lactiforis takii increased by Spartina. Ordination of macroinvertebrate assemblages separated the habitat with Spartina invasion from the adjacent uninvaded tidal flat and Suaeda japonica habitats. This study offers a significant insight into early invasion strategies of an aggressive plant invader, Spartina for management of coastal wetlands and its impacts on macrofaunal assemblages. [ABSTRACT FROM AUTHOR]

Compensatory wetland restoration is a critical component of holistic, ecosystem-level oil spill response strategies. An important goal of restoration is to rehabilitate food webs in impacted areas, but faunal assemblages and trophic dynamics are rarely included in post-restoration monitoring or assessments of success. Different approaches to wetland restoration, including variations in construction technique, may influence faunal recovery and trophic interactions. To explore these dynamics, we compared emergent plant communities, terrestrial arthropod assemblages, and trophic interactions in restored emergent marshes that were constructed in terrace and mound configurations and in reference areas in the Lower Neches Wildlife Management Area (Texas, United States). Plant community composition differed among all habitat types, with higher diversity on terraces and in reference marshes. Terrestrial arthropod abundance was similar among habitat types, but species composition was distinctly different among habitat types, especially at the herbivore level, where four of the eight herbivore species were found in either reference or restored sites, but not in both habitat types. Herbivores (primarily beetles and planthoppers) were more abundant than detritivores (midges and flies) in all habitat types. Predator (web-building and hunting spiders) abundance and species identity were similar among habitat types. Based on stable isotope analysis, trophic relationships differed among mounds, terraces, and reference areas. Herbivore diets were more variable at the reference sites than in either restored habitat type, aligning with higher plant diversity in reference areas. In contrast, detritivore diets were more variable at restored sites, where they were likely consuming food sources such as benthic algae or sediment organic matter. Predator diets were primarily comprised of herbivores in reference areas and detritivores in restored habitats. Overall, the restoration approaches supported abundant terrestrial arthropod assemblages, but species composition was different. In addition, trophic relationships differed between restored and reference areas, in part due to unique plant species assemblages at restored and reference sites. These results suggest that ecosystem restoration strategies that introduce geomorphological heterogeneity and plant diversity are more likely to support a diverse array of species and functions.

Salt marsh vegetation zones shift in response to large‐scale environmental changes such as sea‐level rise (SLR) and restoration activities, but it is unclear if they are good indicators of soil nitrogen removal. Our goal was to characterize the relationship between denitrification potential and salt marsh vegetation zones in tidally restored and tidally unrestricted coastal marshes, and to use vegetation zones to extrapolate how SLR may influence high marsh denitrification at the landscape scale. We conducted denitrification enzyme activity assays on sediment collected from three vegetation zones expected to shift in distribution due to SLR and tidal flow restoration across 20 salt marshes in Connecticut, USA (n = 60 sampling plots) during the summer of 2017. We found lower denitrification potential in short‐form Spartina alterniflora zones (mean, 95% CI: 4, 3–6 mg N h−1 m−2) than in S. patens (25, 15–36 mg N h−1 m−2) and Phragmites australis (56, 16–96 mg N h−1 m−2) zones. Vegetation zone was the single best predictor and explained 52% of the variation in denitrification potential; incorporating restoration status and soil characteristics (soil salinity, moisture, and ammonium) did not improve model fit. Because denitrification potential did not differ between tidally restored and unrestricted marshes, we suggest landscape‐scale changes in denitrification after tidal restoration are likely to be associated with shifts in vegetation, rather than differences driven by restoration status. Sea‐level‐rise‐induced hydrologic changes are widely observed to shift high marsh dominated by S. patens to short‐form S. alterniflora. To explore the implications of this shift in dominant high marsh vegetation, we paired our measured mean denitrification potential rates with projections of high marsh loss from SLR. We found that, under low and medium SLR scenarios, predicted losses of denitrification potential due to replacement of S. patens by short‐form S. alterniflora were substantially larger than losses due to reduced high marsh land area alone. Our results suggest that changes in vegetation zones can serve as landscape‐scale predictors of the response of denitrification rates to rapid changes occurring in salt marshes. [ABSTRACT FROM AUTHOR]

Whole genome duplications (WGDs) lead to polyploid specimens and are regarded as major drivers for speciation and diversification in plants. One prevalent problem when studying WGDs is that effects of polyploidization in ancient polyploids cannot be disentangled from the consequences of selective evolutionary forces. Cytotypic differences in distribution, phenotypic appearance and in response to surface elevation (determined by HOF-modeling) were identified in a relatively young taxa-group of a hexaploid F1-hybrid (Spartina× townsendii H. Groves & J. Groves, Poaceae) and its dodecaploid descendent (Spartina anglica C.E. Hubbard, Poaceae) using vegetation assessments (1029 plots; 1 × 1 m2) from the European Wadden Sea mainland salt marshes, including elevational and mean high tidal (MHT) data. While the F1-hybrid was mainly present in the eastern part of the Wadden Sea, its dodecaploid descendent occurred in the entire Wadden Sea area. The Spartina cytotypes differed in phenotypes (median of Spartina cover: hexaploid = 25% vs. dodecaploid = 12%) and in elevational niche-optimum (hexaploid = − 49.5 cm MHT vs. dodecaploid = 8.0 cm MHT). High ploidy levels correlated with establishment success in Spartina along geographic gradients but did not seem to increase the capacity to cope with abiotic severity downwards the elevational gradient in salt marshes. [ABSTRACT FROM AUTHOR]

The January 2024 issue of Ecological Applications focuses on the topic of biological invasions and their impact on the global environment and economy. The issue includes a special feature on the Management of Biological Invasions in China, which explores strategies for controlling and mitigating invasive species. The cover image of the issue shows the invasion range of S. alterniflora in salt marshes in the Yellow River Delta, China, and highlights the process and pattern of its landward expansion along tidal channels. The image suggests that the meandering geomorphology of tidal channels could facilitate the spread of cordgrass by creating invasion windows. [Extracted from the article]

Biological invasions have become one of the greatest threats to global biodiversity and ecosystem conservation. Most previous studies have revealed how successful invasive species adapt to new environments and climate change through phenotypic and genetic evolution. Some researchers suggested that understanding unsuccessful or less successful biological invasions might be important for understanding the relationships between invasion adaptability and climate factors. We compared the sexual reproduction ability, genetic diversity, and gene × environment interaction in two intentionally introduced alien species in China (Spartina anglica and Spartina alterniflora) based on restriction site-associated DNA (RAD) sequencing. After more than 50 years, the distribution of S. alterniflora has rapidly expanded, while S. anglica has experienced extreme dieback. A total of 212,939 single nucleotide polymorphisms (SNPs) for the two Spartina species were used for analysis. The multilocus genotype (MLG) analysis revealed that clonal reproduction was the prevalent mode of reproduction in both species, indicating that a change in the mode of reproduction was not the key factor enabling successful invasion by Spartina. All genetic diversity indicators (He , Ho , π) in S. alterniflora populations were at least two times higher than those in S. anglica populations, respectively (p < 0.001). Furthermore, the population genetic structure and stronger patterns of climate-associated loci provided support for rapid adaptive evolution in the populations of S. alterniflora in China. Altogether, our results highlight the importance of genetic diversity and local adaptation, which were driven by multiple source populations, in increasing the invasiveness of S. alterniflora. [ABSTRACT FROM AUTHOR]

As global change alters the composition and productivity of ecosystems, the importance of subsidies from one habitat to another may change. We experimentally manipulated black mangrove (Avicennia germinans) cover in 10 large plots and over a 5‐year period (2014–2019) quantifying the effects of mangrove cover on subsidies of floating organic material (wrack) into coastal wetlands. As mangrove cover increased from 0% to 100%, wrack cover and thickness decreased by ~60%, the distance that wrack penetrated into the plots decreased by ~70%, and the percentage of the wrack trapped in the first 6 m of the plot tripled. These patterns observed during 4 "normal" years disappeared in a fifth year following Hurricane Harvey (2017), when large quantities of wrack were pushed far into the interior of all the plots, regardless of mangrove cover. Prior to the storm, the abundance of animals collected in grab samples increased with wrack biomass. Wrack composition did not affect animal abundance or composition. Experimental outplants of two types of wrack (red algae and seagrass) revealed that animal abundance and species composition varied between the fringe and interior of the plots, and between microhabitats dominated by salt marsh versus mangrove vegetation. The importance of wrack to overall carbon stocks varied as a function of autochthonous productivity: wrack inputs (per m2) based on survey data were greater than aboveground plant biomass in the plots (42 × 24 m) dominated by salt‐marsh vegetation, but decreased to 5% of the total aboveground biomass in plots dominated by mangroves. Our results illustrate that increasing mangrove cover decreases the relative importance of marine subsidies into the intertidal at the plot level, but concentrates subsidies at the front edge of the mangrove stand. Storms, however, may temporarily override mangrove attenuation of wrack inputs. Our results highlight the importance of understanding how changes in plant species composition due to global change will impact marine subsidies and exchanges among ecosystems, and foster a broader understanding of the functional interdependence of adjacent habitats within coastal ecosystems. [ABSTRACT FROM AUTHOR]

Climate change is driving abiotic shifts that can threaten the conservation of foundation species and the habitats they support. Directional range shifting is one mechanism of escape, but requires the successful colonization of habitats where interspecific interactions may differ from those to which a species has adapted. For plants with multiple reproductive strategies, these range‐edge interactions may alter the investment or allocation toward a given reproductive strategy. In this study, we quantified sexual reproduction of the clonal marsh grass Spartina patens across an inland colonization front into maritime forest being driven by sea‐level rise. We find that flowering is variable across S. patens meadows, but consistently reduced in low light conditions like those of the forest understory. Observational surveys of S. patens flowering at four sites in the Delmarva Peninsula agreed with the results of two experimental manipulations of light availability (shading experiment in S. patens‐dominated marsh and a forest dieback manipulation). These three approaches pinpointed light limitation as a principal control on S. patens flowering capacity, suggesting that light competition with taller upland species can suppress S. patens flowering along its upland migration front. Consequently, all propagation in shaded conditions must occur clonally or via seeds from the marsh, a reproductive restriction that could limit the potential for local adaptation and reduce genetic diversity. Future research is needed to determine whether the lack of flowering is the result of a trade‐off between sexual and clonal reproduction or results from insufficient photosynthetic products needed to achieve either reproductive method. [ABSTRACT FROM AUTHOR]

The unprecedented size of the deepwater horizon oil spill and scope of the subsequent response elicited intense and sustained interest in microbial responses to oiling, especially in salt marshes, which have featured prominently in debates about best practices to prevent and remediate oiling of vulnerable ecosystems. A number of studies have examined salt marsh soil microbial communities following the spill, but most have primarily concentrated on prokaryotes. The extent to which oiling elicited shifts in fungal diversity and community composition remains unclear. Here we present spatial and temporal comparisons of salt marsh soil fungal communities at two southern Louisiana salt marshes with contrasting oiling histories. We profiled fungal communities in 2013 alongside corresponding measurements of polycyclic aromatic hydrocarbons to assess whether and how responses to oiling are distinguishable from natural heterogeneity. Analyses based on high-resolution unbiased spatial sampling demonstrated that fungal communities did not align with shoreline classification of oiling less than three years after initial oiling, despite observable differences in oil residues and secondary oiling. Notably, extensive sampling allowed delineation of benchmark sampling thresholds and illustrated the value of using ranked differentials of relative abundance to characterize soil fungal communities. Our findings highlight the need for combining high-resolution sampling with judgment-based and systematic sampling approaches to accurately capture responses of salt marsh soil fungal community to oiling. [ABSTRACT FROM AUTHOR]

Salt marshes are ecosystems of significant ecological importance for coastal stability and fundamental roles in marine ecosystems. Salt marshes are declining due to anthropogenic and natural causes including sea level rise. Coastal restoration efforts have increased worldwide, but many fail in long-term coastal stability. We used a naturally occurring arbuscular mycorrhizal fungus (AMF) to test whether survival and early growth of the salt marsh grass Sporobolus pumilus (formerly Spartina patens) improved under simulated salt marsh conditions. Using a tidal mesocosm bench, we grew inoculated plants with varying AMF treatments under simulated tidal regimes to determine if AMF could aid in establishment of healthy Sporobolus communities. Rhizome-derived S. pumilus had greater survival and grew faster than seed-derived plants. Plants inoculated with propagated AMF consistently outperformed both sterile and native sediment controls in terms of plant survival and growth. Use of rhizome-derived Sporobolus inoculated with propagated Funneliformis geosporum showed the most promise in producing successful plant populations for salt marsh restoration. This may be due to plant life stage and improved plant nutrient status, allowing rhizome-derived plants to grow more quickly than seed-derived plants. Using these plants in future large-scale restoration may increase re-establishment of salt marsh ecosystems.

Interspecific interactions between plants influence plant phenotype, distribution, abundance, and community structure. Each of these can, in turn, impact sediment biogeochemistry. Although the population and community level impacts of these interactions have been extensively studied, less is known about their effect on sediment biogeochemistry. This is surprising given that many plants are categorized as foundation species that exert strong control on community structure. In southern California salt marshes, we used clipping experiments to manipulate aboveground neighbor presence to study interactions between two dominant plants, Pacific cordgrass (Spartina foliosa) and perennial pickleweed (Sarcocornia pacifica). We also measured how changes in cordgrass stem density influenced sediment biogeochemistry. Pickleweed suppressed cordgrass stem density but had no effect on aboveground biomass. For every cordgrass stem lost per square meter, porewater ammonium increased 0.3–1.0 µM. Thus, aboveground competition with pickleweed weakened the effects of cordgrass on sediment biogeochemistry. Predictions about plant–soil feedbacks, especially under future climate scenarios, will be improved when plant–plant interactions are considered, particularly those containing dominant and foundation species. [ABSTRACT FROM AUTHOR]

Parallel latitudinal clines in flowering time have been documented in both the invasive and native ranges of plants. Furthermore, flowering time has been found to affect biomass at maturity. Therefore, understanding how these flowering times affect biomass accumulation across latitudes is essential to understanding plant adaptations and distributions.We investigated and compared trends in first flowering day (FFD), aboveground biomass (AGB), belowground biomass (BGB), and BGB:AGB ratio of the salt marsh grass Spartina alterniflora along latitudinal gradients from the invasive (China, 19–40°N) and native range (United States, 27–43°N) in a greenhouse common garden experiment, and tested whether FFD would drive these divergences between invasive and native ranges.The invasive populations produced more (~20%, ~19%) AGB and BGB than native populations, but there were no significant differences in the FFD and BGB:AGB ratio. We found significant parallel latitudinal clines in FFD in both invasive and native ranges. In addition, the BGB:AGB ratio was negatively correlated with the FFD in both the invasive and native ranges but nonsignificant in invasive populations. In contrast, AGB and BGB increased with latitude in the invasive range, but declined with latitude in the native range. Most interestingly, we found AGB and BGB positively correlated with the FFD in the native range, but no significant relationships in the invasive range.Our results indirectly support the evolution of increased competitive ability hypothesis (EICA) that S. alterniflora has evolved to produce greater AGB and BGB in China, but the flowering and allocation pattern of native populations is maintained in the invasive range. Our results also suggest that invasive S. alterniflora in China is not constrained by the trade‐off of earlier flowering with smaller size, and that flowering time has played an important role in biomass allocation across latitudes. [ABSTRACT FROM AUTHOR]

Current theory (e.g., consumer‐controlled theory) predicts that nutrient enrichment typically amplifies herbivory and thereby suppresses the growth and expansion of invasive plants. Herbivores can facilitate plant regrowth in the native community by stimulating complementary growth or ameliorating habitat conditions (e.g., by increasing soil oxygen and nutrient availability), but whether they have similar positive effects on invasive plants, especially under nutrient enrichment, remains unknown. Using a field nitrogen (N)‐enrichment × crab exclusion experiment, we evaluated and compared the effects of both N enrichment and crab herbivory on the growth performance of a global invasive cordgrass, Spartina alterniflora, and a co‐occurring native plant, Phragmites australis. We found that crabs consistently suppressed P. australis by density and aboveground biomass regardless of N enrichment. In contrast, for S. alterniflora, the negative effects of crabs under ambient N were replaced by positive effects under N enrichment, with crabs stimulating complementary increases in density and aboveground biomass. The differing effects between the N treatments were driven by crab burrowing activity, which increased soil N availability, and the nutrient‐use efficiency of S. alterniflora. Our findings revealed that native herbivores can have opposing effects on native and invasive plants, which broadens our understanding of how exotic plants can achieve dominance in a changing world. [ABSTRACT FROM AUTHOR]

Maritime Spartina spp. are powerful ecosystem engineers that accrete sediment, define shorelines, create habitat, and generate prodigious primary productivity both where they are native and where they have been introduced. Invasive Spartina spp. can compete vigorously with native species, diminish biota, change hydrology, and confound human uses of estuaries. Herbicides have been effective in controlling several Spartina spp. invasions. One of the most recent successes is a 15-year campaign that has virtually eliminated S. alterniflora from the large, century-old invasion in Willapa Bay, WA, USA. Hybridization between native and introduced Spartina spp. has created new species and hybrid swarms. In San Francisco Bay, CA, USA (SF Bay) a complicated situation continues to play out from the purposeful introduction of S. alterniflora, which hybridized with native California cordgrass, S. foliosa. The hybrids spread rapidly and led to a long list of environmental problems, which led to an herbicide program that was successful in greatly diminishing the hybrid and saving the open mud habitat of migratory shorebirds. However, it was belatedly realized that the non-migratory, endangered Ridgeway’s rail uses the tall, dense hybrid Spartina as a surrogate for habitat that was lost during the twentieth century to urbanization and agricultural transformation of marshes around SF Bay. This realization has made difficult the simultaneous management of hybrid Spartina, wildlife conservation, and marsh restoration in San Francisco Bay. Restoration of native vegetation could satisfy the multiple goals of preserving open mud and conserving Ridgeway’s rail.

Management actions to protect endangered species and conserve ecosystem function may not always be in precise alignment. Efforts to recover the California Ridgway’s Rail (Rallus obsoletus obsoletus; hereafter, California rail), a federally and state-listed species, and restoration of tidal marsh ecosystems in the San Francisco Bay estuary provide a prime example of habitat restoration that has conflicted with species conservation. On the brink of extinction from habitat loss and degradation, and non-native predators in the 1990s, California rail populations responded positively to introduction of a non-native plant, Atlantic cordgrass (Spartina alterniflora). California rail populations were in substantial decline when the non-native Spartina was initially introduced as part of efforts to recover tidal marshes. Subsequent hybridization with the native Pacific cordgrass (Spartina foliosa) boosted California rail populations by providing greater cover and increased habitat area. The hybrid cordgrass (S. alterniflora × S. foliosa) readily invaded tidal mudflats and channels, and both crowded out native tidal marsh plants and increased sediment accretion in the marsh plain. This resulted in modification of tidal marsh geomorphology, hydrology, productivity, and species composition. Our results show that denser California rail populations occur in invasive Spartina than in native Spartina in San Francisco Bay. Herbicide treatment between 2005 and 2012 removed invasive Spartina from open intertidal mud and preserved foraging habitat for shorebirds. However, removal of invasive Spartina caused substantial decreases in California rail populations. Unknown facets of California rail ecology, undesirable interim stages of tidal marsh restoration, and competing management objectives among stakeholders resulted in management planning for endangered species or ecosystem restoration that favored one goal over the other. We have examined this perceived conflict and propose strategies for moderating harmful effects of restoration while meeting the needs of both endangered species and the imperiled native marsh ecosystem.

Allens Pond, a coastal lagoon in southeastern Massachusetts, was subjected to two major hydrological events in the 2000s. The first was a culvert widening to increase tidal flushing in an attempt to stop the spread of the invasive plant, Phragmites australis. The second, four years later, was a complete inundation of the surrounding salt marsh due to the closure of a tidal inlet. The effect of these events on salt marsh vegetation was monitored using transects and on the marsh avian community using point counts. The inundation event, although limited to one growing season, had a more pronounced negative effect on marsh organisms than the restoration. Saltmarsh cordgrass, Spartina alterniflora, took approximately three years to recover to pre-inundation abundance. Salt marsh hay, Spartina patens, had still not recovered five years after the inundation. This supports the idea that this high marsh plant is particularly sensitive to prolonged inundation. There was no measurable effect of either the hydrological restoration or the inundation event on P. australis. Saltmarsh sparrows declined 79% in the years immediately following the inundation, then recovered to their pre-inundation level in about eight years. Seaside sparrows declined 49% immediately following the inundation event and recovered after eight years, although there was a great deal of variation. Willets were only affected in the year immediately after the inundation. Our results from this flooding incident at Allens Pond provide insight into the potential impact of rising sea levels on estuarine plant and avian communities. [ABSTRACT FROM AUTHOR]

Coastal wetland restoration can be used to offset past wetland losses and/or reduce future losses due to land‐use changes, rising sea levels, and accelerating climate change. However, there is a need for information regarding the restoration‐relevant performance of foundation species like mangrove and marsh plants, including their responses to acute and chronic stressors that can affect restoration outcomes. Mangrove encroachment and poleward range expansion into marsh, facilitated by warming winters, has provided restoration practitioners in the northern Gulf of Mexico with a new foundation plant species to consider using during restoration. To evaluate the performance of transplanted mangroves and characterize restoration‐relevant marsh–mangrove interactions, we planted nursery‐raised black mangrove (Avicennia germinans) seedlings within different marsh cover treatments along an eroding marsh‐dominated shoreline in Louisiana. Mangrove seedling survival increased with greater densities of marsh cover, indicating that marsh grass (Spartina alterniflora) may facilitate mangrove establishment. However, only 35% of transplanted mangrove seedlings established after 10 weeks, suggesting a low return on resources expended in raising seedlings for 1–3 years in greenhouse conditions. Moreover, a 2018 freeze event killed 100% of transplanted mangrove seedlings, while nearby naturally established mangroves suffered minor damage. Our results, along with those in the mangrove restoration literature, indicate that planting mangroves in the northern Gulf of Mexico may not be the most efficient use of limited resources. Rather, restoration efforts may benefit from focusing initially on the restoration of abiotic conditions (e.g. elevation and hydrologic regimes), followed by using marsh plants (rather than transplanted mangroves) to jump‐start ecosystem development. [ABSTRACT FROM AUTHOR]